Coronary Vascular Actions of Synthetic Atrial Natriuretic Factor in Isolated Vascular Preparations

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Abstract
Summary: Administration of atrial natriuretic factor (ANF) in animals results in increases in renal blood flow, natriuresis, and a decrease in arterial blood pressure, supporting a role for the atrial peptide system in cardiovascular regulation. However, little is known about the vascular effects of synthetic ANF (26 amino acid) on coronary artery smooth muscle. We studied the coronary vascular effects of synthetic ANF in feline artery preparations in vitro. In isolated coronary arteries perfused at constant flow, ANF (3–300 nM) concentration dependency decreased perfusion pressure ranging from 2.6 ± 0.7 mm Hg (p < 0.02) at 3 nM to 28.6 ± 3.7 mm Hg (p < 0.001) at 300 nM. Perfusion with the prostacyclin analog, iloprost (20–100 nM), failed to alter the coronary vasodilator response to ANF. ANF also relaxed feline coronary helical strips when contracted by U-46,619 (an en-doperoxide analog), serotonin, and leukotriene D4. This relaxant effect was independent of the presence of endothelial cells and occurred in the presence of a guanylate cyclase inhibitor, methylene blue. The ANF had no direct effect on electrically driven isolated feline papillary muscles, signifying a lack of direct inotropic activity of ANF in cat cardiac muscle. These results suggest that ANF may produce coronary vasodilation that therefore could contribute to coronary regulation, without directly altering myocardial performance.

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